EN
Spin photocurrents generated by homogeneous excitation with terahertz radiation in low dimensional structures are reviewed. Three microscopic mechanisms are responsible for the occurrence of an electric current linked to a uniform spin polarization in a quantum well, the circular photogalvanic effect, the spin-galvanic effect and the magneto-gyrotropic effect. These phenomena provide several methods to investigate various spin properties in low dimensional structures like details of band structure and spin relaxation time.